The present invention relates to a sampling probe for sampling fluids, particularly corrosive fluids and more particularly the invention relates to a sampling device including an inner tube with a flange both made of a synthetic material and an outer tube, also with a flange also made of synthetic material.
A sampling device of the type and kind to which the invention pertains is shown e.g. in German patent 33 05 232. This patent describes a device for taking a hot gas sample from a particular volume of gases, under utilization of a sampling device that can be inserted through an opening in the wall structure confining the gas to be sampled. Moreover a guide tube (4) is secured to that particular wall in the aforementioned opening, for guiding the tubular sampling device. Flange structure is provided at the outer end of that guide tube but in a spaced relation to the wall, and the jacket of the sampling device is releasably secured to that flange. This being the basic structure serving as a point of departure as far as the present invention is concerned. The following should be considered. Genuinely representative sampling of a particular volume often requires to use long sample devices, particularly to reach far in the interior of whatever is being sampled. Depending on the construction and the structural features as they exist it is not always possible to suspend from above the sampling into the volume containing the sampling material. In some cases it may be absolutely necessary to introduce the sample structure laterally i.e. horizontally.
It is very clear, that owing to the inherent weight of the sampling structure there is a certain bending load which is particularly effective as a strong shear load right at the transition between sampling device and fastening flange. This static load may actually be increased owing to the flow speed of the medium and in the case the flow through the sample device is no laminar and smooth, dynamic forces will be experienced, and they pose a superimposing load on the sampling tube.
If the samples taken include corrosive components it is necessary to use fiber reinforced synthetic material for the construction of sample structures, but the mechanical strength of fiber reinforced synthetic is limited to other requirements, particularly where constructions with complex geometries are invloved or just large scale structures have become necessary. One can also use metallic sample devices which are coated with synthetic material. It is assumed then that the coat is porefree but the mechanical protection is insufficient for many fields of use.